For liquid crystal display devices, expansion of viewing angle is a great object for improving display grade, and thus various optical compensation plates have been used for the purpose of optical compensation. One example is a light scattering element for using light scattering. Light scattering denotes a complicated phenomenon including refraction, reflection, interference and diffraction, and it occurs typically when light enters an interface having a refractive index difference. The light scattering element is formed, for example, by forming an irregularity on a surface so as to use difference in the refractive index at an interface between the surface and air, or by dispersing, in a solute, particles or the like having different refractive indices.
Among such light scattering elements, an anisotropic light scattering element having an anisotropy in the light scattering intensity depending on the incidence direction of light can be used for expanding a viewing angle of a liquid crystal display device since the element scatters regions with tone reversal without degrading visibility when viewed from the front.
An example of such anisotropic light scattering elements is prepared by forming a blind-like structure of layers different in the refractive indices by a phase separation so as to generate a diffraction phenomenon and develop an anisotropy of light scattering (see, e.g., JP 64(1989)-77001). However, this anisotropic light scattering element is difficult to put into practical use, since, for example, control of its anisotropy in the scattering is complicated and the thickness of the element will be increased (e.g., several hundreds of μm).
Another example of an anisotropic light scattering layer is prepared by dispersing isotropic particles in a translucent medium having an anisotropy (see, e.g., JP 11(1999)-29772). However, control of the scattering direction is restricted, and thus sufficient optical compensation may not be provided.